Inhibition of sodium-glucose cotransporter 2 suppresses renal stone formation

Structural characterization of polysaccharides from Lygodium japonicum (Thunb.) Sw. and its inhibition ability in calcium oxalate renal stone

BACKGROUND

Kidney stone is a prevalent abnormal mineralization disease characterized by high incidence and recurrence rates. Current pharmacological interventions for kidney stone predominantly rely on potassium citrate (PC), yet its clinical efficacy remains limited. Lygodium japonicum (Thunb.) Sw., which possesses both edible and medicinal values, is one of the most commonly used herbs in traditional Chinese medicine for treating urinary tract stones; however, its material basis and underlying mechanisms remain unclear.

METHODS

a l. japonicum polysaccharide (LJP) with a molecular weight of 12.9 kDa was obtained through hot-water extraction and purification. The structure of LJP was characterized, and its role in inhibiting kidney stone formation was investigated.

RESULTS

LJP primarily consists of Glc, Gal-UA, Glc-UA, Gal, Rha, and Ara monosaccharides, with the main chain mainly composed of →4)-α-d-Glcp-(1→ linkages, along with minor amounts of →2)-α-d-Glcp-(1→, →2,6)-α-d-Glcp-(1→, →3,6)-β-d-Glcp-(1→, →4,6)-β-d-Glcp-(1→, →3)-α-d-Glcp-(1→. LJP is able to specifically adsorb onto high-energy (1¯01) crystal surfaces to inhibit calcium oxalate monohydrate (COM) growth, significantly reducing crystal size and promoting phase conversion from COM to calcium oxalate dihydrate (COD). Additionally, it effectively inhibits crystal adhesion and endocytosis. LJP also exhibits excellent antioxidant properties, mitigating cellular oxidative stress induced by nano-COM crystals, reducing mitochondrial, lysosomal, and DNA damage, and inhibiting cell apoptosis. In addition, LJP can be effectively enriched in rat kidneys, significantly inhibiting calcium oxalate (CaOx) crystal formation in vivo and reducing renal injury. Metabolomic profiling revealed that LJP mainly affects the citric acid cycle and purine metabolic pathways. Compared to PC, a conventional stone treatment drug, LJP demonstrates superior performance in modulating CaOx crystalline form and cytoprotection.

CONCLUSION

LJP may serve as a promising therapeutic option for the treatment of renal stones.

Use of Sodium-Glucose Transport Protein 2 Inhibitors and the Incidence of Urolithiasis: A Multi-Database and Cross-Country Study in Patients With Type 2 Diabetes Mellitus

The benefits of sodium-glucose transport protein 2 inhibitor (SGLT2i) use on severe urolithiasis requiring surgery remains unclear. All patients with incident T2D in Taiwan National Health Institution databases (2016-2021) and TriNetX datasets (2014-2023) were retrospectively analyzed. The study analyzed a propensity score-matched pairs with T2D treated with SGLT2i or dipeptidyl peptidase 4 inhibitors (DPP4i). The primary outcome was the incidence of urolithiasis and urolithiasis requiring surgery during the study period. Urolithiasis diagnoses were identified using International Classification of Diseases diagnostic codes and categorized into upper and lower urinary tract stones. Cases of urolithiasis requiring surgery were determined by the presence of both diagnostic codes and surgical procedure codes within the same outpatient visit or hospitalization. Conditional and time-dependent Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During the study period, 5700 participants were diagnosed with urolithiasis, 1297 participants were urolithiasis requiring surgery in Taiwan NHIRD cohort 8438 participants with urolithiasis as well as 289 participants with urolithiasis requiring surgery were in the TriNetX cohort. Adjusted HRs of urolithiasis and urolithiasis requiring surgery were 0.82-fold (95% CI, 0.77-0.87), 0.72-fold (95% CI, 0.63-0.82) in Taiwan NHIRD, 0.84 (95% CI, 0.78-0.90), and 0.62 (95% CI, 0.44-0.88) in TriNetX cohort respectively. Similar protective associations with SGLT2i use against urolithiasis were observed across subgroups in both datasets from Taiwan NHIRD and TriNetX. In conclusion, SGLT2i might protect against kidney stones and severe cases requiring surgery in T2D patients.

Study protocol for a randomized single-center cross-over study: Dapagliflozin treatment in recurring kidney stone patients

INTRODUCTION

Urolithiasis is one of the most common diseases worldwide, characterized by high morbidity and significant treatment-related costs, with a rising prevalence of up to 20%. The relapse rate within the first 10 years after initial treatment is estimated to be about 60%. Given the increasing prevalence, healthcare-related costs associated with urinary tract stones in the USA are expected to reach up to US $1.24 billion annually by 2030. Current prophylactic therapy for urolithiasis recurrence includes lifestyle modifications, citrate supplementation, and pharmaceuticals. However, a high number of cases remain unresponsive to available pharmacological therapies. Though initially developed for the treatment of Diabetes mellitus, SGLT-2 inhibitors have shown promise in decreasing cardiac and renal endpoints across multiple indications. Recent registry studies have indicated that patients receiving SGLT-2 inhibitors exhibit lower rates of urolithiasis incidence, suggesting a potential reduction in recurrence rates and associated mortality.

OBJECTIVES

We hypothesize that SGLT-2 inhibitors (Dapagliflozin), owing to their multiple pleiotropic effects, may offer a viable treatment option for the prophylaxis of high-risk calcium oxalate kidney stones and reduce urinary calcium oxalate output.

METHODS

This study will proceed in two phases: an exploratory phase and a randomized controlled phase. In the exploratory phase, 22 participants with indications for dapagliflozin treatment will be evaluated before and after treatment initiation to ascertain the concrete effect size regarding oxalate and calcium-sparing effects. This data will inform the calculation of the study sample size (ranging from 17 to 104 participants) to include high-risk calcium oxalate kidney stone formers in a randomized controlled crossover study design. Treatment phases-one with dapagliflozin and one with placebo-will alternate with wash-out phases involving placebo. The primary outcome is the reduction of oxalate excretion in 24-hour urine samples compared to baseline values after 8 weeks of therapy. Secondary objectives include analysing effects on kidney function, the frequency of urolithiasis, and treatment tolerance. Additionally, in-depth metabolomics analyses will explore pathophysiological pathways during treatment. Investigators, patients, and research staff will be blinded to the randomization list. This study was initially registered under EudraCT (Nr:2022-000994-13) and has been transitioned to CTIS (Nr: 2024-519371-25-00) to comply with EU Regulation 536/2014, ensuring streamlined management and transparency.

DISCUSSION

Dapagliflozin's pleiotropic effects may provide a novel prophylactic treatment option for urolithiasis. This study aims to evaluate potential treatment effects in a prospective RCT and elucidate potential pathophysiological pathways through in-depth metabolomics analyses. SGLT-2 inhibitors have the potential to transform the landscape of urolithiasis treatment, reduce the healthcare burden on individuals and the system, and significantly improve patient quality of life.

Sodium glucose co-transporter 2 inhibitor prevents nephrolithiasis in non-diabetes by restoring impaired autophagic flux

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) offer significant cardiovascular and kidney protection, independent of diabetes mellitus (DM). Recent cohort studies also suggest that SGLT2i can decrease the risk of nephrolithiasis in patients with DM. We aimed to use both animal models and human data to investigate whether SGLT2i can prevent nephrolithiasis and explored autophagy as a possible mechanism.

METHODS

We utilised SGLT2i, dapagliflozin (DAPA), on a glyoxylate (GOX)-induced calcium oxalate (CaOx) nephrolithiasis non-DM mouse model to test whether SGLT2i inhibited CaOx stone formation through modulating autophagy. Moreover, the clinical data retrieved from the National Health Insurance Research Database was analysed to confirm the findings from animal models.

FINDINGS

DAPA increased urine citrate, magnesium, pH, and decreased oxalate, effectively inhibiting CaOx stones in GOX mice. While autophagy was increased in the kidneys of GOX mice, as demonstrated by upregulated AMP-activated protein kinase (AMPK) and increased LC3B conversion; impaired autophagic flux was indicated by p62 accumulation. DAPA improved autophagy by downregulating mammalian target of rapamycin (mTOR), AMPK, and restoring autophagic flux. Rapamycin co-treatment preserved DAPA's nephrolithiasis inhibition, while hydroxychloroquine (HCQ) co-treatment abolished it. Finally, cohort data confirmed that SGLT2i reduced nephrolithiasis risk, but this protective effect disappeared if HCQ had been used within the prior year, suggesting that HCQ may compromise SGLT2i's protection against nephrolithiasis.

INTERPRETATION

SGLT2i, DAPA, inhibits nephrolithiasis by restoring impaired autophagic flux, and co-administration with autophagy inhibitor, HCQ, compromises SGLT2i's protection.

FUNDING

This research was funded by grants from the National Science and Technology Council, Taiwan (110-2314-B-006-023, 110-2320-B-006-017MY3, and 112-2314-B-006-058) and the research grants (NCKUH-11202005, -11210020) from the National Cheng Kung University Hospital, Tainan, Taiwan.

SGLT2 inhibitors and nephrolithiasis risk: a meta-analysis

BACKGROUND

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are novel anti-diabetic medications with potential beneficial effects on cardiovascular and renal outcomes, metabolic parameters and body weight. In addition to the beneficial effects on renal function, including estimated glomerular filtration rate and reduction in proteinuria, recent studies have investigated the potential role of SGLT2 inhibitor (SGLT2i) therapy on nephrolithiasis development. Nephrolithiasis, a condition affecting almost 10% of the general population at least once during a lifetime, is a common disorder with considerable risk for acute and chronic kidney injury and relatively few effective therapeutic options.

METHODS

We performed a literature search through multiple databases, including PubMed, Ovid MEDLINE, Web of Science, Scopus and Cochrane Library. We followed the systematic review and meta-analysis guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We included a total of 11 635 698 patients who experienced nephrolithiasis from six clinical trials in this meta-analysis study.

RESULTS

In the pooled analysis, nephrolithiasis occurred in 1.27% of patients in the SGLT2i group (n = 739 197), compared with 1.56% of patients (n = 10 896 501) in the control arm (active control, placebo or no therapy). SGLT-2 inhibitor therapy has been associated with a lower risk for nephrolithiasis compared with placebo {odds ratio [OR] 0.61 [95% confidence interval (CI) 0.53-0.70], P < .00001} or active therapy such as glucagon-like peptide 1 and dipeptidyl peptidase 4 inhibitors [OR 0.66 (95% CI 0.47-0.93), P = .02].

CONCLUSION

We demonstrated a lower risk of nephrolithiasis with SGLT2i therapy compared with placebo or active control. Potential underlying mechanisms include osmotic diuresis leading to a reduction in the concentration of lithogenic substances, anti-inflammatory and anti-fibrotic effects and an increase in urine pH. There is a clear need for future large-scale randomized clinical trials evaluating such associations for better understanding.

Construction of arginine vasopressin receptor 2-deficient rats by the rGONAD method

BACKGROUND

Congenital nephrogenic diabetes insipidus (NDI) is a hereditary disease characterized by a reduced response to arginine vasopressin in the renal collecting duct. NDI is primarily caused by mutations in the arginine vasopressin receptor 2 (AVPR2). Several animal models have been developed for congenital NDI; however, the appropriate models are limited. Thus, we constructed a novel Avpr2-deficient rat model using gene-editing technology to study the pathophysiological mechanisms of NDI.

METHODS

Avpr2-deficient rats were generated via a novel genome editing approach termed the rat Genome-editing via Oviductal Nucleic Acid Delivery (rGONAD) method. The phenotypes were analyzed using biological, molecular, and histological examinations. The effects of hydrochlorothiazide (40 mg/kg/d) on 24-h water intake, urine volume, and urine osmolality were evaluated in a metabolic cage.

RESULTS

Avpr2-deficient rats were born and weaned under normal rearing conditions and exhibited symptoms similar to those of human congenital NDI, such as polydipsia, polyuria, and growth retardation. Although they exhibited hydronephrosis-like kidneys, no glomerular or tubular damage was observed. Aquaporin-2 was retained in the cytoplasm of collecting duct cells, and its phosphorylation was suppressed. Administration of hydrochlorothiazide decreased urine volume and improved urine osmolality in Avpr2-deficient rats.

CONCLUSIONS

Avpr2-deficient rats are a reliable model of congenital NDI for elucidating the underlying mechanisms and identifying therapeutic targets.

Inhibition of NLRP3 alleviates calcium oxalate crystal-induced renal fibrosis and crystal adhesion

Kidney stones are gaining attention as one of the most common urological diseases. In this study, we first constructed a mouse model of calcium oxalate (CaOx) crystal deposition by intraperitoneal injection of glyoxalate (Gly) and found that the levels of NLRP3, CASP1 and ASC, which constitute the NLRP3 inflammasome, as well as the level of its downstream product, IL-1β, were elevated in the kidneys of the model group of mice, as determined by RNA-seq. We then examined NLRP3 expression via immunohistochemistry, immunofluorescence, qPCR, and Western blotting in human samples, calcium oxalate monohydrate (COM)-stimulated HK2 cells, and a model of calcium oxalate crystal deposition via intraperitoneal injection. We then constructed systemic NLRP3 knockout mice and found via RNA-seq that CaOx crystal-induced renal fibrosis and crystal adhesion may be attenuated after the knockout of NLRP3. We further substantiated these findings by knocking down NLRP3 both in vitro and in NLRP3-knockout mice. Consistently, we observed more pronounced calcium oxalate crystal-induced renal fibrosis and enhanced crystal adhesion upon overexpression of NLRP3 in vitro and in vivo. Ultimately, we utilized the NLRP3 inhibitor MCC950 to support the potential of NLRP3 as a therapeutic target. Our research revealed that NLRP3 plays a pivotal role in kidney stone formation by mitigating renal fibrosis and reducing crystal adhesion induced by CaOx crystals.

Involvement of Cholinergic and Cyclooxygenase Pathways in the Diuretic Effects of Rosmarinic Acid

Rosmarinic acid (RA) is a natural antioxidant known for its diverse biological activities. Although its diuretic activity has been previously established, the mode of action remained unclear. To investigate this, we examined the diuretic activity of RA alone and in combination with hydrochlorothiazide (HCTZ), amiloride (AML), atropine (ATR), and indomethacin (INDO) to see if any of these drugs could interfere with RA's activity in an 8 hour acute diuresis animal model. We observed that RA increases urine excretion and may have a synergistic effect in the HCTZ+RA group, with a potassium-sparing capacity. In the AML+RA group, we also noted increased urine excretion while sodium and potassium excretion decreased. ATR and INDO prevented RA from increasing urine excretion, suggesting a potential interaction with muscarinic receptors or a role in promoting prostaglandin production. Additionally, molecular docking analysis indicated possible interactions with key receptors involved in increased diuresis or free-electrolyte water excretion.

Risk of Nephrolithiasis Associated With SGLT2 Inhibitors Versus DPP4 Inhibitors Among Patients With Type 2 Diabetes: A Target Trial Emulation Study

OBJECTIVE

We aim to compare the risk of nephrolithiasis among type 2 diabetes patients who initiated sodium-glucose cotransporter 2 inhibitors (SGLT2is) versus dipeptidyl peptidase 4 inhibitors (DPP4is), individually within stone never- and ever-formers.

RESEARCH DESIGN AND METHODS

Using the 2010-2021 Korea National Health Insurance Service database, we conducted a population-based cohort study, comparing initiators of SGLT2is versus DPP4is. The primary outcome was incident nephrolithiasis. Osteoarthritis encounters served as a negative control outcome. After 1:1 propensity score (PS) matching in stone never- and ever-formers, pooled and individual hazard ratios (HRs), incidence rate difference (IRD), and 95% CIs were reported. Subgroup analyses by sex, age, thiazide co-use, and baseline cardiovascular risk were done.

RESULTS

The 17,006 PS-matched pairs of SGLT2i and DPP4i initiators were pooled from stone never-formers (105,378 pairs) and ever-formers (11,628 pairs). Over a mean of 654 days, the risk of nephrolithiasis was lower in SGLT2i initiators than in DPP4i initiators: 0.65 vs. 1.12 events per 100 person-years, HR 0.54 (95% CI, 0.50-0.57), IRD -0.46 (95% CI, -0.21 to -0.52). Among never-formers, the HR was 0.43 (95% CI, 0.39-0.48) and IRD was -0.32 (95% CI, -0.27 to -0.36). Among ever-formers, the HR was 0.64 (95% CI, 0.59-0.69) and IRD was -2.26 (95% CI, -1.77 to -2.76). Near-null associations were found for osteoarthritis encounters. Results were consistent across subgroups.

CONCLUSIONS

We found a lower risk of nephrolithiasis associated with SGLT2is versus DPP4is in stone never- and ever-formers. Despite a greater relative risk reduction in the former, the absolute risk reduction was greater in the latter.

Secondary hyperoxaluria: Cause and consequence of chronic kidney disease

Secondary hyperoxaluria is a metabolic disorder characterized by an increase in urinary oxalate excretion. The etiology may arise from an increase in the intake of oxalate or its precursors, decreased elimination at the digestive level, or heightened renal excretion. Recently, the role of the SLC26A6 transporter in the etiopathogenesis of this disease has been identified. This transporter is active at both the intestinal and renal levels, and its mechanism of action is disrupted during systemic inflammation and metabolic syndrome, which could explain the rising incidence of secondary hyperoxaluria in recent decades. Treatment includes hygienic dietary measures, and medications aimed at reducing intestinal absorption by increasing fecal excretion. Different immunomodulatory drugs, microbiome modifiers and SGLT2 inhibitors could constitute new therapeutic targets. Currently, specific treatments for secondary hyperoxaluria are lacking, making early diagnosis and preventive measures against kidney failure the main therapeutic strategies.

Empagliflozin in nondiabetic individuals with calcium and uric acid kidney stones: a randomized phase 2 trial

Efficacy of sodium-glucose cotransporter 2 inhibitors for kidney stone prevention in nondiabetic patients is unknown. In a double-blind, placebo-controlled, single-center, crossover phase 2 trial, 53 adults (≥18 and <75 years) with calcium (n = 28) or uric acid (UA; n = 25) kidney stones (at least one previous kidney stone event) without diabetes (HbA1c < 6.5%, no diabetes treatment) were randomized to once daily empagliflozin 25 mg followed by placebo or reverse (2 weeks per treatment). Randomization and analysis were performed separately for both stone types. Primary analyses were conducted in the per protocol set. Primary outcomes were urine relative supersaturation ratios (RSRs) for calcium oxalate (CaOx), calcium phosphate (CaP) and UA-validated surrogates for stone recurrence. Prespecified RSR reductions (≥15%) were met in both groups of stone formers. In patients with calcium stones, empagliflozin reduced RSR CaP (relative difference to placebo, -36%; 95% confidence interval, -48% to -21%; P < 0.001), but not RSRs CaOx and UA. In patients with UA stones, empagliflozin reduced RSR UA (-30%; 95% confidence interval, -44% to -12%; P = 0.002) but not RSRs CaOx and CaP. No serious or prespecified adverse events occurred. Thus, empagliflozin substantially reduced RSRs in nondiabetic adults with calcium and UA kidney stones. ClinicalTrials.gov registration: NCT04911660 .

Isovaleramide attenuates ethylene glycol poisoning-induced acute kidney injury and reduces mortality by inhibiting alcohol dehydrogenase activity in rats

We explored the potential value of the alcohol dehydrogenase (ADH) inhibitor isovaleramide (ISO) in the treatment of acute ethylene glycol (EG) poisoning-induced acute kidney injury. Sprague-Dawley rats were divided into the control, EG, EG + ISO (10 mg/kg) and EG + ISO (20 mg/kg) groups. It is found that ISO intervention significantly reduced the ADH activity in liver tissue by using visible spectrophotometry, inhibited the in vivo metabolism of EG by using gas chromatography, lowered the levels of toxic metabolites glycolic acid and oxalic acid by using high-performance liquid chromatography and decreased the expression of kidney injury markers serum creatinine (sCr), KIM-1, neutrophil gelatinase-associated lipocalin (NGAL) and liver fatty acid-binding protein (L-FABP) by ELISA. Additionally, Western blotting results showed that ISO down-regulated the expression of apoptotic factors Bax and cleaved caspase-3 in the kidneys and upregulated the expression of antiapoptotic factor Bcl-2. Pizzolato staining and polarized light microscopy results revealed the reduced deposition of calcium oxalate crystals in the kidney tubules. Using haematoxylin and eosin (H&E), periodic acid-Schiff (PAS) and Masson staining, we found attenuated kidney tissue pathological injury. Finally, ISO significantly reduced the mortality rate. In conclusion, ISO has the potential to be a valuable drug for the treatment of EG poisoning-induced acute kidney injury.

SGLT2 Inhibitors and Their Effect on Urolithiasis: Current Evidence and Future Directions

Urolithiasis (UL) is increasingly prevalent due to rising cardiorenometabolic diseases, posing significant management challenges despite advances in urological techniques. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, primarily used for type 2 diabetes mellitus, chronic kidney disease, and heart failure, have emerged as a potential novel approach for UL treatment. These inhibitors may help reduce the risk of urolithiasis, particularly in patients with diabetes, by improving glycemic control and altering urinary chemistry, which are crucial factors in stone formation. However, the changes in urinary composition induced by SGLT2 inhibitors might also increase the risk of uric acid stone formation. This review evaluates the potential of SGLT2 inhibitors in managing UL, highlighting both the benefits and the risks. While these inhibitors show promise in reducing new and recurrent urinary stones in patients with diabetes, data on their effects in patients without diabetes who form stones are limited. Current human evidence largely comes from post hoc analyses of randomized controlled trials (RCTs) and large-scale database studies, with only one study providing detailed stone composition data. Experimental studies in animal models and cell lines have focused on calcium oxalate (CaOx) stones, showing that SGLT2 inhibitors specifically target CaOx stone formation and related renal inflammation. Although primarily studied for CaOx stones, their potential impact on other calcium-containing stones, such as calcium phosphate, remains promising. Further research is needed to explore their therapeutic potential and optimize treatment strategies.

Lithocarpus polystachyus Rehd. ameliorates cerebral ischemia/reperfusion injury through inhibiting PI3K/AKT/NF-κB pathway and regulating NLRP3-mediated pyroptosis

Introduction

Ischemic stroke (IS) is a serious threat to human life and health, and cerebral ischemia/reperfusion injury (CIRI) exacerbates IS by enhancing neuroinflammation and oxidative stress. Sweet tea (ST) comprises several bioactive components, such as phlorizin, trilobatin, and phloretin, with diverse pharmacological activities. However, it remains uncertain whether ST can confer protection against CIRI. In this study, we aimed to investigate the impact and potential underlying mechanism of ST in the context of CIRI.

Methods

CIRI model were established in male sprague dawley (SD) rats. The neurobehavioral assessment, the volume of cerebral infarction and the morphology of neurons were measured to complete the preliminary pharmacodynamic study. The therapeutic targets and pathways of ST on IS were obtained by protein-protein interaction, molecular docking and Metascape database. The predicted results were further verified in vivo.

Results

Our results revealed that ST treatment significantly ameliorated brain damage in rats subjected to CIRI by mitigating mitochondrial oxidative stress and neuroinflammation. Additionally, we identified the PI3K/AKT/NF-κB pathway and the NLRP3-mediated pyroptosis axis as crucial processes, with molecular docking suggested direct interactions between the main compounds of ST and NLRP3.

Conclusion

ST safeguards against CIRI-induced neuronal loss, neuroinflammation and oxidative stress through the inhibition of the PI3K/AKT/NF-κB pathway and the regulation of NLRP3-mediated pyroptosis.

Sodium-glucose cotranspor ter 2 (SGLT2) inhibitors in nephrolithiasis: should we "gliflozin" patients with kidney stone disease?

The prevalence of nephrolithiasis is increasing worldwide. Despite advances in understanding the pathogenesis of lithiasis, few studies have demonstrated that specific clinical interventions reduce the recurrence of nephrolithiasis. The aim of this review is to analyze the current data and potential effects of iSGLT2 in lithogenesis and try to answer the question: Should we also "gliflozin" our patients with kidney stone disease?

Prevention, diagnosis, and treatment of urolithiasis in geriatric patients - differences, similarities and caveats in comparison to the general population

PURPOSE OF REVIEW

Purpose of the review is to address management and prevention of urolithiasis in elderly patients examining the dynamic interplay between general measures, dietary adjustments, lifestyle modifications, and targeted pharmacological and/ or surgical interventions. The goal is to provide understanding of the evolving strategies required for effective urolithiasis prevention in the geriatric population.

RECENT FINDINGS

Age-specific diagnostic considerations are necessary because urolithiasis in the elderly population is characterized by bigger stones, greater peri-operative risks, and heightened symptom severity. When comorbidities are present, conservative treatments - especially analgesia - provide difficulties. Surgical procedures prove to be safe and effective, with complication rates and practical application comparable to younger cohorts. Prevention approaches that include lifestyle changes and the investigation of novel pharmaceutical options such as sodium-dependent glucose co-transporter 2 (SGLT-2)-inhibitors are promising in the management of urolithiasis in the elderly population.

SUMMARY

Our review offers a thorough investigation of urolithiasis in the elderly population, elucidating distinct clinical manifestations, complex diagnostic issues, and treatment implications. The safety and effectiveness of ureteroscopy in older patients, as well as the possible prophylactic function of SGLT-2-I, offer crucial insights for clinicians. Subsequent studies are necessary to enhance age-specific therapies, addressing the distinct obstacles presented by urolithiasis in the elderly population within this rapidly growing demographic.

Sodium-Glucose Cotransporter 2 Inhibitors and Nephrolithiasis Risk in Patients With Type 2 Diabetes

Importance

Type 2 diabetes (T2D) is associated with an increased risk of kidney stones. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) might lower the risk of nephrolithiasis by altering urine composition. However, no studies have investigated the association between SGLT2i use and nephrolithiasis risk in patients receiving routine care in the US.

Objective

To investigate the association between SGLT2i use and nephrolithiasis risk in clinical practice.

Design, Setting, and Participants

This new-user, active comparator cohort study used data from commercially insured adults (aged ≥18 years) with T2D who initiated treatment with SGLT2is, glucagon-like peptide 1 receptor agonists (GLP-1RAs), or dipeptidyl peptidase 4 inhibitors (DPP4is) between April 1, 2013, and December 31, 2020. The data were analyzed from July 2021 through June 2023.

Exposure

New initiation of an SGLT2i, GLP-1RA, or DPP4i.

Main Outcomes and Measures

The primary outcome was nephrolithiasis diagnosed by International Classification of Diseases codes in the inpatient or outpatient setting. New SGLT2i users were 1:1 propensity score matched to new users of a GLP-1RA or DPP4i in pairwise comparisons. Incidence rates, rate differences (RDs), and estimated hazard ratios (HRs) with 95% CIs were calculated.

Results

After 1:1 propensity score matching, a total of 716 406 adults with T2D (358 203 pairs) initiating an SGLT2i or a GLP-1RA (mean [SD] age, 61.4 [9.7] years for both groups; 51.4% vs 51.2% female; 48.6% vs 48.5% male) and 662 056 adults (331 028 pairs) initiating an SGLT2i or a DPP4i (mean [SD] age, 61.8 [9.3] vs 61.7 [10.1] years; 47.4% vs 47.3% female; 52.6% vs 52.7% male) were included. Over a median follow-up of 192 (IQR, 88-409) days, the risk of nephrolithiasis was lower in patients initiating an SGLT2i than among those initiating a GLP-1RA (14.9 vs 21.3 events per 1000 person-years; HR, 0.69 [95% CI, 0.67-0.72]; RD, -6.4 [95% CI, -7.1 to -5.7]) or a DPP4i (14.6 vs 19.9 events per 1000 person-years; HR, 0.74 [95% CI, 0.71-0.77]; RD, -5.3 [95% CI, -6.0 to -4.6]). The association between SGLT2i use and nephrolithiasis risk was similar by sex, race and ethnicity, history of chronic kidney disease, and obesity. The magnitude of the risk reduction with SGLT2i use was larger among adults aged younger than 70 years vs aged 70 years or older (HR, 0.85 [95% CI, 0.79-0.91]; RD, -3.46 [95% CI, -4.87 to -2.05] per 1000 person-years; P for interaction <.001).

Conclusions and Relevance

These findings suggest that in adults with T2D, SGLT2i use may lower the risk of nephrolithiasis compared with GLP-1RAs or DPP4is and could help to inform decision-making when prescribing glucose-lowering agents for patients who may be at risk for developing nephrolithiasis.

Sodium glucose cotransporter 2 inhibitor suppresses renal injury in rats with renal congestion

Renal congestion is an issue of cardiorenal syndrome in patients with heart failure. Recent clinical and basic studies suggest a renoprotective potential of sodium-glucose cotransporter (SGLT) 2 inhibitors. However, the effect on renal congestion and its mechanism is not fully understood. Thus, we aimed to clarify the effect of SGLT inhibition in a renal congestion model. Renal congestion was induced in the left kidney of male Sprague-Dawley rats by ligation of the inferior vena cava between the renal veins. The SGLT2 inhibitor tofogliflozin or vehicle was orally administered daily from the day before IVC ligation until two days after surgery. On the third postoperative day, both the right control kidney and the left congested kidney were harvested and analyzed. Kidney weight and water content was increased, and renal injury and fibrosis were observed in the left congested kidney. Kidney weight gain and hydration were improved with tofogliflozin treatment. Additionally, this treatment effectively reduced renal injury and fibrosis, particularly in the renal cortex. SGLT2 expression was observed in the congested kidney, but suppressed in the damaged tubular cells. Molecules associated with inflammation were increased in the congested kidney and reversed by tofogliflozin treatment. Mitochondrial dysfunction provoked by renal congestion was also improved by tofogliflozin treatment. Tofogliflozin protects against renal damage induced by renal congestion. SGLT2 inhibitors could be a candidate strategy for renal impairment associated with heart failure.

Pericyte detachment and renal congestion involve interstitial injury and fibrosis in Dahl salt-sensitive rats and humans with heart failure

Congestive heart failure produces fluid volume overload, central and renal venous pressure elevation, and consequently renal congestion, which results in worsening renal function. Pericyte detachment and pericyte-myofibroblast transition (PMT) were linked to renal interstitial fibrosis. Dahl salt-sensitive hypertensive (DahlS) rats are a non-surgical renal congestion model. The relation, however, between renal interstitial damage, pericyte morphology, and PMT in the renal congestion of DahlS rats has not been reported. DahlS rats (8-week-old) were fed normal salt (NS, 0.4% NaCl) or high salt (HS, 4% NaCl), and the left kidney was decapsulated to reduce renal interstitial hydrostatic pressure (RIHP) at 9 weeks old. One week after capsulotomy, both kidneys were analyzed by molecular and histological techniques. Renal pericyte structure was assessed in the body donors with/without venous stasis. Markers of tubulointerstitial damage, interstitial fibrosis, and PMT were upregulated in the right non-decapsulated kidney of DahlS rats fed HS. Renal tubular injury and fibrosis were detected in the HS diet groups in histological analysis. Pericyte detachment was observed in the right non-decapsulated kidney of DahlS rats fed HS by low vacuum-scanning electron microscopy. Decapsulation in DahlS rats fed HS attenuated these findings. Also, renal pericytes detached from the vascular wall in patients with heart failure. These results suggest that pericyte detachment and PMT induced by increased RIHP are responsible for tubulointerstitial injury and fibrosis in DahlS rats and humans with renal congestion. Renal venous congestion and subsequent physiological changes could be therapeutic targets for renal damage in cardiorenal syndrome.

The Association between Dietary Sugar Intake and Nephrolithiasis: Results from National Health and Nutrition Examination Survey 2007-2018

BACKGROUND

Dietary sugar intake is gradually considered a risk factor for many diseases. A sugary diet was positively associated with risk of nephrolithiasis, but the specific relationships remain undefined.

OBJECTIVES

To determine associations between risk of nephrolithiasis and dietary sugar intake.

METHODS

This cross-sectional study involved 21,590 participants based on the National Health and Nutrition Examination Survey from 2007 to 2018. Amounts of dietary sugar intake (g/d) were the main exposure, including total sugar intake, added sugar intake, and food sources. Associations were analyzed by logistic regression models and restricted cubic splines using complex weighted designs.

RESULTS

Weighted mean intake [standard error] of total sugar and added sugar were 111.2 [2.0] g/d and 73.7 [1.9] g/d in participants with nephrolithiasis, respectively. In the fully adjusted regression model, compared to those in quartile 1, the population in quartile 4 of total sugar intake showed a significant risk of nephrolithiasis [odds ratio (OR): 1.23; 95% confidence interval (CI): 1.00-1.51]; OR for added sugar intake was 1.56 (95% CI: 1.25-1.94). The risks of nephrolithiasis increased steadily when total sugar and added sugar intake exceeded ∼150 g/d and 63 g/d in restricted cubic spline analyses, respectively. The highest sugar intake from beverages was associated with an increased risk of nephrolithiasis (OR for total sugar: 1.36; 95% CI: 1.07-1.72; OR for added sugar: 1.37; 95% CI: 1.09-1.73). Added sugar intake from meat, egg, and oil was significantly associated with risk of nephrolithiasis (quartile 4, OR: 1.22; 95% CI: 1.02-1.47), whereas total sugar intake from dairy products was in reverse (quartile 4, OR: 0.67; 95% CI: 0.54-0.82).

CONCLUSIONS

Total and added sugar intake, sugar intake from beverages, and added sugar intake from meat, egg, and oil were associated with an increased risk of nephrolithiasis, whereas total sugar intake from dairy products was negatively associated.

Oxalate (dys)Metabolism: Person-to-Person Variability, Kidney and Cardiometabolic Toxicity

Oxalate is a metabolic end-product whose systemic concentrations are highly variable among individuals. Genetic (primary hyperoxaluria) and non-genetic (e.g., diet, microbiota, renal and metabolic disease) reasons underlie elevated plasma concentrations and tissue accumulation of oxalate, which is toxic to the body. A classic example is the triad of primary hyperoxaluria, nephrolithiasis, and kidney injury. Lessons learned from this example suggest further investigation of other putative factors associated with oxalate dysmetabolism, namely the identification of precursors (glyoxylate, aromatic amino acids, glyoxal and vitamin C), the regulation of the endogenous pathways that produce oxalate, or the microbiota's contribution to oxalate systemic availability. The association between secondary nephrolithiasis and cardiovascular and metabolic diseases (hypertension, type 2 diabetes, and obesity) inspired the authors to perform this comprehensive review about oxalate dysmetabolism and its relation to cardiometabolic toxicity. This perspective may offer something substantial that helps advance understanding of effective management and draws attention to the novel class of treatments available in clinical practice.

Quantitative effects of sodium-glucose cotransporter-2 inhibitors on liver functions in patients with nonalcoholic fatty liver disease

BACKGROUND

The present study aimed to explore the quantitative effects of sodium-glucose cotransporter-2 (SGLT-2) inhibitors on liver functions in patients with nonalcoholic fatty liver disease (NAFLD).

RESEARCH DESIGN AND METHODS

A total of 4771 patients with NAFLD were included for analysis by means of nonlinear mixed effect modeling, where the change rates of liver functions were taken as the evaluation indexes so as to eliminate the potential baseline effects.

RESULTS

For ALT and AST, the Emax of SGLT-2 inhibitors was -17.8% and -13.9%, respectively, and the ET50 was 6.86 weeks and 10 weeks, respectively. Furthermore, the duration time to achieve 25%, 50%, 75%, and 80% Emax were 2.3 weeks, 6.86 weeks, 20.6 weeks, 27.5 weeks in ALT, 3.4 weeks, 10 weeks, 30 weeks, 40 weeks in AST, respectively. Thus, to realize the plateau period (80% of Emax) of SGLT-2 inhibitors on ALT and AST in patients with NAFLD, 100 mg/day canagliflozin (or 10 mg/day dapagliflozin or 10 mg/day empagliflozin) needs to be taken for 20.6 weeks and 30 weeks, respectively.

CONCLUSIONS

The present study explored the quantitative effects of SGLT-2 inhibitors on liver functions and recommends a therapeutic regimen in patients with NAFLD.

Untargeted and targeted metabolomics reveal bile acid profile changes in rats with ethylene glycol-induced calcium oxalate nephrolithiasis

Calcium oxalate (CaOx) nephrolithiasis is a prevalent disorder linked to metabolism. Examining metabolic alterations could potentially give an initial understanding of the origins of CaOx nephrolithiasis. This study aims to determine gut metabolic biomarkers differentiating CaOx nephrolithiasis utilizing untargeted and targeted metabolomics. CaOx nephrolithiasis model rats were built by 1% ethylene glycol administration. Histologic staining and renal function measurement revealed the presence of crystals in the lumen of the renal tubules, the renal injury and interstitial fibrosis in CaOx rats, demonstrating that the models of CaOx were established successfully. Hematoxylin & eosin (H&E) staining showed that CaOx group had inflammation and damage in the ileal tissue. Immunofluorescence and PCR results displayed that the tight junction proteins, ZO-1 and Occludin levels were decreased in the ileal tissues of the CaOx group. The untargeted metabolomic analysis revealed that 269 gut metabolites were differentially expressed between the CaOx group and the control group. Meanwhile, bile secretion, the main metabolic pathway in CaOx nephrolithiasis, was identified. Following, five significant bile acid metabolites were selected utilizing the targeted bile acid metabolomics, including Hyodeoxycholic acid (HDCA), Glycohyodeoxycholic acid (GHDCA), Nor-Deoxycholic Acid, omega-muricholic acid, and Taurolithocholic acid. Among these metabolites, HDCA and GHDCA presented the highest predictive accuracy with AUC = 1 to distinguish the CaOx group from the control group. As a result of network pharmacology, target genes of HDCA and GHDCA in CaOx nephrolithiasis were enriched in oxidative stress and apoptosis pathways. Conclusively, our study provides insight into bile acids metabolic changes related to CaOx nephrolithiasis. Although alterations in biochemical pathways indicate a complex pathology in CaOx rats, bile acid changes may serve as biomarkers of CaOx nephrolithiasis.